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Comment by pktgen | Hacker News Reader

> We wouldn't give someone a raw, unfettered machine in our datacenter (and I hope you wouldn't either!).

I think you're alluding to security issues with renting bare metal hardware to potentially untrusted customers, right? I've often wondered about the security implications of that - think backdooring BIOS/UEFI or other component firmware. But there are many large providers that rent dedicated hardware without a hypervisor. Are they just ignoring these concerns, hoping that this kind of tampering would be rare anyway?

> What is your concern with virtualization in this context?

I'm not the parent poster, but performance was probably the concern. There's still some (marginal, these days) overhead with virtualization in general, and VT-d specifically.

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From our perspective: yes, we don't feel comfortable letting untrusted users run side by side without a sandbox.

In this context though of GPU compute, you are just talking sporadically to a PCIe attached device directly. There isn't any virtualization or sharing of the device. And yes, I assumed that the complaint would be performance, but especially with just a pass through GPU, it's going to be honestly funny to find the right "oh wow this is 20% slower because virtualization specifically".

> From our perspective: yes, we don't feel comfortable letting untrusted users run side by side without a sandbox.

That's what I figured. I still wonder what other large providers (SoftLayer, OVH, etc.) do about this. Unfortunately, I suspect the answer is "nothing, we just hope/assume nothing will happen."

> In this context though of GPU compute, you are just talking sporadically to a PCIe attached device directly.

I know; I'm familiar with passthrough. It's not completely "free," but the overhead is very minor. I don't think anyone will be able to complain with a straight face about its performance. :P

> But there are many large providers that rent dedicated hardware without a hypervisor. Are they just ignoring these concerns, hoping that this kind of tampering would be rare anyway?

Yes. You can try to mitigate the risk a bit, but it's still there. Just think of all the other firmware you can update, not just UEFI.

Also, for large contracts, rented servers are usually bought new and not re-used for multiple reasons (this is why providers have used server markets!).

Virtualization overhead is so low nowadays that it's not worth the risk. Provisioning is much harder, too.

> Virtualization overhead is so low nowadays that it's not worth the risk

The entire Finance industry would like to disagree with you.

On the other hand, you don't run latency sensitive code in the cloud, you run on your own hardware. Since GCE is a cloud, no reason not to have the virtualization.

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